Overview of Main Sensory Organs and Their Function PDF

Overview of main sensory organs and their function Laura Andreae We perceive the world, in all its detail, using our senses These are our sense organs: eyes, ears, tongue and nose… …which contain sensory receptors – specialised cells (often neurons) that can convert information about external wor...

Overview of main sensory organs and their function Laura Andreae We perceive the world, in all its detail, using our senses These are our sense organs: eyes, ears, tongue and nose… …which contain sensory receptors – specialised cells (often neurons) that can convert information about external world into a signal that our brain can understand. This process is called sensory transduction: For example, the eye converts light waves into a neural signal using photoreceptors in the retina Webvision, U. Utah While the ear converts sound waves into a neural signal using mechanoreceptors Sensory receptors Sensory Receptors There are different types of sensory receptors: Thermoreceptors Pain receptors Mechanoreceptors Chemoreceptors Electromagnetic receptors  Sensory Receptors There are different types of sensory receptors: Thermoreceptors Pain receptors Mechanoreceptors Chemoreceptors Electromagnetic receptors Receptors are specialised to detect different types of stimuli Receptors generate an electrical signal – receptor potential Sensory Receptors There are different types of sensory receptors: Thermoreceptors Pain receptors Mechanoreceptors Chemoreceptors Electromagnetic receptors  Sensory Transduction TASTE Signal transduction pathway Taste bud Na+ Adapted from Campbell Biology  Sensory Transduction SMELL Concepts of Biology  Sensory Transduction SMELL PSYC Open courses Sensory Receptors There are different types of sensory receptors: Thermoreceptors Pain receptors Mechanoreceptors Chemoreceptors Electromagnetic receptors  Sensory Transduction VISION  Sensory Transduction Photoreceptors VISION Disc  Sensory Transduction VISION Disc Retinal Rhodopsin Opsin Adapted from Campbell Biology VISION VISION Normal retina Retinitis Pigmentosa Sensory Receptors There are different types of sensory receptors: Thermoreceptors Pain receptors Mechanoreceptors Chemoreceptors Electromagnetic receptors  Sensory Transduction HEARING  Sensory Transduction HEARING Openstax College  Sensory Transduction HEARING Openstax College  Sensory Transduction HEARING What-when-how.com HEARING Coding for stimulus properties  Sensory Transduction But also need to somehow encode key properties of sensory stimulus: For example: TASTE  Sensory Transduction But also need to somehow encode key properties of sensory stimulus: vs How strong is it?  Sensory Transduction But also need to somehow encode key properties of sensory stimulus: vs Which taste?  Sensory Transduction In general, the intensity of the stimulus is reflected in the amplitude of the receptor potential So, the stronger the stimulus the bigger the receptor potential So, the stronger the stimulus the bigger the receptor potential Adapted from Campbell Biology Action potentials are ‘all or none’ so have relatively fixed strength. Bigger receptor potential = More neurotransmitter release = Higher rate of AP firing  Sensory Transduction In general, the intensity of the stimulus is reflected in the amplitude of the receptor potential So, the stronger the stimulus the bigger the receptor potential And therefore the faster the rate of action potential firing in the sensory neuron  Sensory Transduction What about different TYPES of stimulus?  Sensory Transduction Sweet Salty Different types of taste? Different types receptor cells Sensory Transduction SMELL We use a similar approach for smell – just a bit more complicated! We have 100-200 different types of odorant receptor. By using combinations of these, we can discriminate thousands of different smells! VISION Colour? We distinguish colour by combining the 3 types of cone VISION Colour? We distinguish colour by combining the 3 types of cone Eg: orange light activates red cones and green cones to specific levels VISION But what about… Position? Object recognition? Movement? Etc… Visual system VERY complicated! VISION Position? VISION Position? HEARING VS  Frequency of the sound wave ~ pitch HEARING Coded by position along the cochlea  Learning Outcomes Describe the function of the different sensory organs Explain how different types of sensory receptors are used in different sense organs Understand principles of how information regarding the strength or type of stimulus may be communicated to the brain  Reading list Kandel and Schwartz – ‘Principles of Neural Science’ Squire et al “Fundamental Neuroscience” Any standard Neuroscience textbook – chapter(s) on Sensory Perception